Heat pump



Aug. 18, 1942. E. R. AMBROSE HEAT PUMP Filed June 26, 1941" 3 Sheets Sheet l To Outdoors To Room gTo outdo ors Inventor. Eugen R. Ambrose, by iVa/m yijw H15 Attovney.

Aug. 18, 1942. i:. R. AMBROSE HEAT PUMP Filed June 26, 1941 3 Sheets-Sheet 2 Fig.2.

Invehtdr: Eugene FR. Am brose,

His Attorn ey- I z- 1942. a R. AMBROSE 2,293,432

' mm PUMP I Filed June ,26, 1941 V s sheets-shena- "Fig.4.

Inventor: Eugene R. Am brose,

f/wwy. .(7

His Attorney.

Patented Aug. 18 1942 UNITED STATES PATENT "OFFICE HEAT PUMP Eugene R. 'Ambrose, Oranford, N. 1., assignor to General Electric Company, a corporation of New York Application June 26, 1941, Serial No. 399,840

11 Claims. (01. 62-6) My invention relates to air conditioning systwo evaporatorsconnected in a closed refrigerant terns and particularly to such systems which circuit, the evaporators being connected in parutilize heat pumps or reversible refrigerating allel in the refrigerant circuit. A duct structure machines for both heating and cooling. is provided to form three air circulating zones as A refrigerating machinemay be utilized in an shown each having a blower or air circulating air conditioning system for both heating and fan for directing air therethrough. The comcooling by providing some suitable arrangement pressor and condenser are arranged in the first for selectively reversing the direction of flow of zone, one evaporator in the second zone, and the heat between the air in the enclosure or room to other evaporator in the third zone. During the be conditioned and the outdoor air or other heat ng Se o air for the enclosuretobe heated medium employed for supplying or removing is circulated over the condenser and compressor heat. For example, the refrigerant circuit of the unit in the first zone and outdoor air over the refrigerating machine of a cooling system may evaporators in the other zones. During the cool be reversed for heating so that the evaporator ing season outdoor air is circulated through the becomes a condenser and the condenser an evapl5 first zone and air to be cooled and admitted to orator, or the air paths of such a system may be the enclosure is circulated through the third zone, reversed to change from the cooling to the heatand under certain conditions of operation the ing operation so that the air for the enclosure blower in the second zone may be employed as a flows over the condenser instead of over the evapbooster to augment the circulation of outdoor air orator while the external medium flows over the produced by the blower in the first or in the third evaporator-instead of over the condenser. zone. The control of the dampers is automatic It is an object of my invention to provide an and is effected in accordance with changes in the air conditioning system employing a refrlgeratrequirements of the system as determined, for ing machine as a heat pump and including an example, by the temperature of the outdoor air. improved arrangement for controlling selectively 2. Referring now to the drawings in- Fig. 1, I have the air paths over the heat absorbing and heat shown an air conditioning system comprising a dissipating surfaces of the refrigerating machine. duct structure or housing In providing three Another object of my invention is torprovide zones or compartments I]; I2, and I3 through an air conditioning system including a refrigerwhich air may be circulated by operation. of ating machine having heat absorbing and heat motor-driven fans l4, l5 and 16, respectively. dissipating surfaces arranged for the circulation The air flowing through the compartment ll of air thereover, and having an improved armay be heated and .the air flowing through comrangement for controlling the system including partments l2 and I3 may be cooled by operation the air paths thereof to provide a more effective of a refrigerating machine comprising a comutilization of the capacity of the refrigerating pressor I1, driven by a motor II, a condenser is machine. and evaporators 20 and 2| all connected in a Further objects and advantages of my inven-- closed refrigerant circuit. The-compressor unit tion will become apparent as the following deand the condenser constitute heat dissipating scription proceeds and the features of novelty elements and the evaporators constitute heat airwhich characterize my invention will be pointed sorbing elements. The compressor l1 and the out with particularity in the claims annexed to motor II are arranged in the compartment I I and forming a part of this specification. and the condenser is is arranged in a discharge For a better understanding of my invention hood 22 in the outlet of the compartment. reference may be had to the accompanying draw- The fan H is driven by a motor 23 mounted in ings in which Fig. 1 is'a diagrammatic view of the inlet of the hood 22., The compressor I! an air conditioning system embodying my invendelivers hot compressed refrigerant to the contion; Fig. 2 is a line-to-line diagram of the elecdenser 19 through a connection 2|, and refrigtrical control circuit for the system shown in erant liquefied in the condenser l9 flows to a Fig. l; and Figs. 3 to 6 inclusive, are diagramliquid receiver 25 within the compartment ll. matlc views similar to Fig. 1 illustrating the sev- The fans It and II are driven by motors 31 and oral positions or the dampers. for controlling the It. r s t ve y. n d in nl t connections .ilow of air. 89 and 40 of their respective compartments.

Briefly, the air conditioning system illustrated Evaporators 20 and 2! are connected in parallel in the drawings comprises a refrigerating main the refrigerant circuit by liquid lines 26 and chine including a compressor, a condenser and 2l, respectivelv, and suction lines 28 and 29, re-

spectively. vaporized refrigerant flowing from the refrigerator through the suction lines 28 and 23 returns to the compressor through a common suction line 30. A normally closed valve 3! is arranged in the liquid line 25'and may be operated by a solenoid 32 to admit refrigerant to the evaporator 20, the flow of refrigerant being controlled by a thermostatic expansion valve 33 in the usual manner. Similarly, a normally closed valve 34 is provided in the connection 21 and may be opened by operation of a solenoid 35 to admit refrigerant to the evaporator 2|, the flow of refrigerant being controlled by a thermostatic expansion valve 36.

A system of duct work is provided so that either room air or outdoor air may be circulated through the three compartments and discharged to the outdoors, or to the room, depending on the conditions of operation of the system. 'I'he compartment II is provided with an inlet ductr4l arranged to receive outside or fresh air from an inlet 42 under control of dampers 43 and to receive room air through an inlet, 44 under control of dampers 45. The air circulated through the compartment H is discharged through a duct 45 and may enter the room through an outlet 41 under control of dampers 48 or may be discharged to the outdoors through an outlet 49 under control of dampers '50. The compartment I2 is provided with an outdoor air inlet duct and the compartment I3 is provided with a room'air inlet duct 52 for receiving air from-the room under control of dampers 53. A cross-duct 54 is arranged between the ducts 5| and 52 and is provided with control dampers 55 havin a minimum closedposition determined by a stop 56,- The duct 54 makes it possible to admit outdoor air from the duct 5| tothe compartment I3. Air

may be discharged from the compartment l2 to the outdoors through a duct 51 under control of dampers 53, and air may be discharged from the compartment l3 through a duct 59 and into the room through an outlet 50 controlled by dampers 51 or into the duct 51 through a cross-duct '32 under control of dampers 63. 7 Between the compartments II and I2 there is provided a duct or connection 54 controlled by dampers 65 so that air may be circulated from the compartment 12 into the compartment II. All of the dampers above referred to are of the normally closed type and may be actuated to their open positions by the operation of solenoids in a manner to be described.

The air'conditioning system just described may 7 be employed for maintaining the desired air co'n-' ditioning temperature in the room throughout all the seasons of the year.

'During the heating season air is circulated through the compartment I l and is discharged into the room through duct 41, the dampers 45 and "being open and the dampers 43 and 50 being closed. Some fresh air will be taken in at all times since the dampers 43 are provided with a stop 56 for preventing their-- complete closing. When the system is being employed in this manner to heat the air in the room, outdoor air is circulated through one or both of the compartments l2 and I3 and is returned to the outdoors through the duct 51. The dampers 58 are open when the compartment I2 is employed and the I dampers 56 and 83 are also open when both comof a four-armed switch 80' and moves the switch l2 and I3 and is supplied to the air flowing through the compartment l I, the heat being dissipated to the air by the condenser and compressor unit. 1

During the cooling season, the dampers 43 and 50 are kept open to circulate outdoor air through the compartment II and remove heat from the refrigerating apparatus while room air is circulated through the compartment l3 and back into the room through the opening 50, dampers 53 and GI being open. The air admitted to the compartment I3 may be a mixture of room air and fresh air drawn in through the dampers 55 in their limited closed position, or it may be entirely outdoor air provided the dampers 53 are closed and the dampers 55 opened. The evaporator 20 is not normally used to cool air during the cooling season but the fan 15 may be employed to augment the flow of outdoor air. through the compartment II by opening the dampers 55 thereby providing a'booster for the fan-l4.

The operation of the system during the heating season is controlled by a heating thermostat 10 and the operation during the cooling season is controlled by a cooling thermostat 1|; the control of the air paths has been shown as effected inaccordance with the operation of four thermostats 12, 13, 14 and 15 all responsive to the temperature of the outdoor air, although it is obvious that other load responsive control or manual control might be employed. The manner in which the control is effected will readily be apparent from the control diagram shown in Fig. 2. Power for energizing the control circuits and for driving the fan and compressor motors is supplied from power lines 16 and 11 and a manual switch 13 is provided to interrupt the power supply. w

i In the following description, in order to provide an example of the setting of the controls, it is assumed that the thermostat 12 closes its contacts when the outdoor air is above 65 F., the thermostat 13 closes its contacts when the temperature is above 60 F., the thermostat 14 closes drawings, only the thermostat 13'has been indi-' cated in its closed position in which case the temperature would be below 65 F. and above 60 F.

In the following, the operation of the system will be described assuming that the manual switch 18 is closed to start the operation at a time when the outdoor temperature is below 50 F. and that the operation of the system continues while the outdoor temperature rises to a temperature higher than 65 F.

At temperatures below 50 .F. the entire heating capacity of the refrigerating machine is made available," both thermostats 14 and "being in their closed positions. When the switch 13 is closed the thermostat 15 actuates a solenoid 13 to its upper or closed position. The lowest arm of the switch closes the circuit of a solenoid ll which actuates'the dampers 63 to their open position. The next lowest arm of the switch closes the circuit of a solenoid 82 which moves the dampers 55 to their openpositiom The third switch arm from the bottom closes the circuit of the solenoid 35 to open the refrigerant supply valve 34 of the evaporator 2|, and the top arm of the switch closes the circuit of fan motor 33 to start the operation of fan I6.

The thermostat 14 in its closed position energizes a solenoid 83 of a four-armed switch 84 and closes the switch. The lowermost contact arm of the switch closes the circuit of solenoids 85, 88 and 81 connected in parallel and arranged to actuate the dampers 45, 48 and 58 respectively to their open positions. The next arm of the switch 84 prepares the circuit of the solenoid 82 so that it may be operated on a demand for heat determined by the thermostat 18. The third arm from the bottom of switch 84 prepares the circuit of the compressor motor I8 so that the compressor will be started on a demand for heat, and the top arm of the switch 84 closes a cir cult of the fan motors 23 and 31 connected in parallel, thereby starting the fans I4 and I5. All the fan motors are thus started upon closing of the manual switch 18, and the'dampers45, 48,.

55, 58 and 83 are opened. The circulating air paths for this position of the control are illustrated in Fig. 3 of the drawings from which it is evident that a mixture of fresh air and room air is circulated through compartment II and into the room while outdoor air is circulated through both compartments I2 and I3 over the evaporators and back to the outdoors. Upon a demand for heat the thermostat 18 will close its contacts thereby, connecting a solenoid 88 in the secondary circuit of a transformer 88 and actuating a four-armed switch 88 to its upper position. The two lower arms of the switch 88 complete the circuits of the solenoid 32 and of the compressor motor |8 and the refrigerating machine is thereby operated, so that the evaporators 28 and 2| absorb heat from the outdoor air circulated through the compartments l2 and I8 and the air circulated through'the compartment II is heated by the compressor unit and the condenser and then supplied to the room. When the thermostat 18 is satisfied and opens its contacts operation of the refrigerating machine is stopped, however, the circulation of air continues. When the outdoor air reaches a temperature above 58 F. the thermostat 15 opens its contacts and the switch 88 drops out thereby deenergizing the solenoids 8| and 82 and allowing the dampers 84 and 85 to return to their closed positions; ,at the same time the two upper arms of the switch 88 opens the circuits of the fan motor 38 and the solenoid 35 thereby stopping the operation of r the fan I8 and shutting off the supply of refrigerant to the evaporator 2| In this position the controls the compartment I3 is not utilized to augment the floor of outdoor air which now is circulated only through the compartment I2 and over the evaporator 28 as shown in Fig. 4; andupon a demand for heat there will be a smaller evaporator surface for the absorption of heat from the outdoor air. The capacity of the refrigerating machine has thus been reduced in view of the decreased load requirement as determined by the outdoor temperature.

As the outdoor temperature continues to rise and reaches a temperature of 60 F., the thermostat 14 opens its contacts and deenergizes the solenoid 83 causing the switch 84 to drop out, thereby deenergizing solenoids 82, 85, 88 and 81 to close the valve 3| and stop the operation of the evaporator 28 and to allow the dampers, 45, 48 and 58 to move to their closed positions. The fan motors 23 and 31 and the compressor motor I8 are also deenergized so that the entire system is shut down momentarily, however, as soon'as the temperature increases to a value above- 60 energize a solenoid 8| of a four-armed switch 82. The lowermost arm of the switch 82 prepares a circuit of a solenoid 88 for operating the dampers 53 upon a call for heat by the thermostat 18. The next to the lowest arm of the switch 82 energizes the circuit of the solenoid 82 to open the dampers 55 provided the thermostat 18 is not calling for heat. The second arm from the top of the switch 82 energizes the circuit of a solenoid 84 to open the dampers 8|, and the top arm of the switch 82 energizes a circuit of the fan motor 88 to start the operation of the fan I8. The operation of the refrigerating system between temperatures of 60 F. and 65 F. is indicated in Fig. 5; this position of the apparatus is such that outdoor air is brought into the compartment |8 through the cross-duct 54, the dampers 55 being open and theair is circulated through the compartment I8 and 'flows into the room through the outlet 88, the dampers 8| being open. The refrigerating machine. is not in operation. Should the thermostat 18 call for heat, the switch 88 will be moved to'its upper position thereby deenergizing the solenoid '82 since the top arm of the switch 88 opens the circuit established by the next to the lowest arm of the switch 82. This I closes the dampers 55 so that only the minimum amount of fresh air is drawn into the compartment I3 and at the same time the second arm from top of the switch 88 closes the circuit of the solenoid 83 established by the lowermost arm of the switch 82 and thereby opens the dampers 53 so that room air is recirculated by operation of the fan I8. The refrigerating machine remains idle.

As the outdoor temperature continues to rise to a value greater than 65, F. the thermostat 12 closes its contactsto energize a solenoid 85 0! a five-armed switch 88. The middle arm of the switch 88 energizes the circuit of three solenoids 81, 88, and 88 which open'the dampers 48, 58 and 85, respectively. The bottom arm of the switch 88 closes a circuit energizing the motors 23 and 31 and starts the operation of the fans I4 and I5, the next to the'bottom arm of the switch 26 closes the solenoid 83 thereby opening the dampers 53. The top arm of the switch 88 prepares a circuit of thesolenoid 85 so that the valve 34 will be opened upon a demand for-cooling determined by the thermostat 1|, and the next to the top arm of the switch 88 prepares a circuit of the compressor motor I8. Should there be a demand for cooling, the thermostat 1| closes its contacts and connects a solenoid I88 across the primary winding of a transformer I8I thereby picking up a switch I82 and energizing the circuits of the solenoid 85 and the motor, I8 to "start the refrigerating machine.

. The operation of the system during this period F. th thermostat 13 will close its contacts and and 8| being in their open positions.

is indicated in Fig. 6. Outdoor air is circulated through the compartment II from the inlet 42 to the outlet 48 by operation of the fan I4, and the flow of outdoor air through the compartment II is augmented by the operation of the fan I5 which circulates outdoor air from the connection 5| through the compartment I2 and into the compartment through the connection 84. A mixture of room air and outside air is circulated from theconnection 52 through the compartment I3 and into the room, the dampers 58, 55 The air for theroom is cooled by operation of the refrigerating machine which is connected to supply 'refrig'erant'to the evaporator 2|. The evaporator 28 is not in use and the dampers58 are closed.

refrigerating system. during the cooling season. During the cooling season, whenever the ther mostat .II is not calling for cooling, the refrigerating machine is idle, but the fans continue to operate and circulate air through the several compartments. Should the suction pressure or back pressure of the compressor decrease below a predetermined minimum permissible value a bellows I03 will contract and open a switch I04 thereby opening the circuit of the compressor motor [8 and preventing operation of the compressor until the suction pressure again rises to the working range.

The operation of the air conditioning system as described above will be effected in reverse order when the outdoor temperature falls from 65 F. to atemperature below 50 F. It is readily apparent that the system will operate over a wide range of outdoor temperatures providing either heating or cooling as required and that it will modify the capacity of the refrigerating machine depending upon the temperature of the outdoor air. The operation of the system is automatic after it has been started by closing the manual switch 18. The system will continue to maintain the desired range of temperature under control of the thermostat 10 during the cooling season and under control of the thermostat H during the heating season. The direction of flow of heat between the enclosure and the outdoors may be varied without the necessity of reversing or otherwise changing the refrigerant circuit. The

several compartments of this system and the circulating fans are so arranged that the most desirable conditions of operation are maintained automatically for any given outdoor temperature.

Although I have described my invention in connection with an air conditioning system, other applications will readily be apparent .to those skilled in the art. I do not, therefore, desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An i1; conditioning system including a first compartment and a. second compartment and a third compartment, each of said compartments being provided with a separate air inlet and a separate blower for circulating air therethrough, and means including dampers for determining selectively the paths of air flowing from said inlets through said compartments, said means being operable in one position of said dampers to utilize the blower of said second compartment for assisting the blower in said first compartment to augment the circulation of air produced by ond compartment and a third compartment, each of said compartments being provided with a separate blower for circulating air therethrough, a

refrigerating machine including a heat dissipating element in said first compartment and heat absorbing elements in said second and third compartments, damper means operable in a first position for affording a circulation of air from said enclosure through said first compartment and back to said enclosure and in a second posi-' tion for afiording a circulation of air from outside said enclosure through said first compartment and back to the outside, damper means operable in a first position for affording a circulation of outside air through said third compartment to the outside and in a second position for affording a circulation of air from theenclosure through said third compartment and back to the enclosure, damper means operable in a first position for affording a circulation of outside air through said second compartment and in a second position for utilizing the fan in said second compartment, to force outside air into said first compartment, means dependent upon a predetermined low temperature of the air outside said enclosure for actuating said three damper means to their first positions and dependent upon a predetermined higher temperature of the air outside said enclosure for actuating said three damper means to their second positions.

3. A system for conditioning the air within an enclosure including a refrigerating machine having a heat dissipating element and two heat absorbing elements, each of said elements having a separate fan for circulating air thereover, and means selectively operabl into a first position for utilizing said refrigerating'machine to heat the air in the enclosure and into a second position for utilizing said refrigerating machine to cool the air in the enclosure, said means in said first position directing outside air over both said heat absorbing elements and directing air circulated over said heat dissipating element into the enclosure, said means in said second position directing outside air over said heat dissipating element and directing air circulated over one of said heat absorbing elements into the enclosure and utilizing the fan of the other of said heat absorbing elements to augment the circulation of outside air over said heat dissipating element.

4. A system for conditioning the air within an enclosure including a refrigerating machine having a heat dissipating element and two heat absorbing elements, each of said elements having a separate fan for circulating air thereover, and means selectively operable into first and second positions for utilizing said refrigerating machine to heat the air in the enclosure and into a third position for utilizing said refrigerating machine to cool the air in the enclosure, said means in said first position directing outside air over both of 'said heat absorbing elements and directing air circulated over said heat dissipating element into the enclosure, said means in said second position directing outside air over one only of said heat absorbing elements and directing air circulated over said'heat dissipating element and into the enclosure, said means in said third position directing outside air over saidrheat dissipating element and directing air circulated over one of said heat absorbing elements into the enclosure and utilizing the fan of the other of said heat absorbing elements to augment the circulation of outside air over said heat'dissipating-element.

5. An air conditioning system including a refrigerating machine for heating and for cooling the air in an enclosure, said refrigerating machine including a heat dissipating element and two heat absorbing elements, each of said elements having an individual fan for circulating air thereover, and air control means selectively operable to a first position to'utilize said machine to pump heat into the enclosure and selectively operable to a second position for utilizing said machine to pump heat out of the enclosure, said means in its first position being arranged to direct outside air over said two heat absorbing elements and to direct air over said heat dissipating element and into the enclosure and in its second position to direct outside air over said heat dissipating element and to direct air over one of said heat absorbing elements and into the enclosure, said means in its second position utilizing the fan of the other of said heat absorbing elements to augment the flow of air over said heat dissipating element.

6. An air conditioning system including a refrigerating machine for heating and for cooling .the air in an enclosure, said refrigerating machine including a heat dissipating element and two heat absorbing elements, each of said elements having an individual fan for circulating air thereover, and air control means selectively operable to a first position to utilize said machine to pump heat into the enclosure and selectively operable to a second position for utilizing said machine to pump heat out of the enclosure, said means in its first position being arranged to direct outside air over said two heat absorbing elements and to direct air over said heat dissipating element and into the enclosure and in its second position to direct outside air over said heat dissipating element and to direct air over one of said heat absorbing elements and into the enclosure, said means in its second position utilizing the fan of the other of said heat absorbing elements to augment the flow of air over said heat dissipating element, and means dependent upon a predetermined temperature of the outside air for operating said air control means to its first position and dependent upon a predetermined higher temperature of the outside air for operating said air control means to its second position.

7. An air conditioning system including a refrigerating machine for heating and for cooling the air in an enclosure, said refrigerating machine comprising a condenser and a compressor and two evaporators connected in a closed refrigerant circuit, valve means for shutting off the supply of refrigerant to one of said evaporators, a fan for circulating air over said condenser, individual fans for circulating air over each of said evaporators, and air control means selectively operable to a first position to utilize said machine to pump heat into the enclosure and selectively operable to a second position for utilizing said machine to pump heat out of the enclosure, said air control means in its first position being arranged to direct outside air over said two evaporators and to direct air over said condenser and into the enclosure and in its second position to direct outside air over said condenser and to direct air over the other one of said evaporators and into the enclosure, said air control means in said second position actuating said valve means to cut off the flow of refrigerant to said one evaporator and utilizing the fan of said one evaporator to augment the fiow of air over said condenser.

8. An air conditioning system including a refrigerating machine for heating and for cooling the air in an enclosure, said refrigerating machine comprising a condenser and a compressor and two evaporators connected in a closed refrigerant circuit, valve means for shutting off the supply of refrigerant to one of said evaporators, a fan for circulating air over said condenser, individual fans for circulating air over each of said evaporators, and air control means selectively operable to a first position to utilize said machine to pump heat into the enclosure and selectively operable to a second position for utilizing said machine to pump heat out of the enclosure, said air control means in its first position being arranged to direct outside air over said two evaporators and to direct air over said condenser and into the enclosure and in its second position to direct outside air over said condenser and to direct air over the other one of said evaporators and into the enclosure, said air control means in said second position actuating said valve means to cut off the fiow of refrigerant to said one evaporator and utilizing the fan of said one evaporator to augment the fiow of air over said condenser, and temperature responsive means dependent upon temperatures of the outside air below a predetermined temperature for actuating said air control means to its first position and dependent upon temperatures of the outside air above a predetermined temperature for actuating said air control means to its second position.

9. An air conditioning system including a refrigerating machine for heating and for cooling the air in an enclosure, said refrigerating machine comprising a condenser and a compressor and two evaporators connected in a closed refrigerant circuit, means providing a first compartment and including a fan for circulating air first over said compressor and then over said condenser, means providing a second compartment and including a fan for circulating air over one of said evaporators, means providing a third compartment and including a circulating fan for circulating air over the other of said evaporators, valve means for shutting off the supply of refrigerant to said one of said evaporators, and

damper means selectively operable to a first position to utilize said machine and said fans to pump heat into the enclosure and selectively operable to a second position to utilize said machine and said fans to pump heat out of the enclosure, said damper means in its first position being arranged to direct outside air through said second and third compartments and to direct air through said first compartment and into the enclosure and in its second position to direct outside air through said first compartment and to direct air through said third compartment and into the enclosure, said damper means in said second position actuating said valve means to cut out the fiow of refrigerant to said one evaporator and utilizing the fan in said second compartment to circulate air from said second compartment into said first compartment intermediate said compressor and said condenser to augment the flow of air over said condenser.

10. A system for conditioning the air within an enclosure including a refrigerating machine having a heat dissipating element and a heat absorbing element, a fan associated with said heat dissipating element for circulating air thereover, a fan associated with said heat absorbing element for circulating air thereover, thermostatic means dependent upon the temperature of the air in said enclosure for controlling the operation of said refrigerating machine, means dependent upon a temperature of the outdoor air above a first predetermined temperature for directing into the enclosure air circulated over said heat absorbing element and for rendering said thermostatic means eifective to control the operation of said refrigerating machine, means dependent upon a temperature of the outdoor air below a second predetermined temperature for directing into'the enclosure air circulated over said heat dissipating element and for rendering said thermostatic means effective to control the operation of said v refrigerating machine, and means dependent upfor circulating air thereover, thermostatic means dependent upon the temperature of the air in said enclosure for controlling the operation of said refrigerating machine, means dependent upon a temperature of the outdoor air above a first predetermined temperature for directing into the enclosure air circulated over said heat absorbing element and for rendering said thermostatic means eifective to control the operation of said regfrigerating machine, means dependent upon a temperature of the outdoor air below a second predetermined temperature for directing into the enclosure air circulated over said heat dissipating element and for rendering said thermostatic means effective to control the operation of said refrigerating machine, and means dependent upon temperatures of the outdoor air in the range between said first and second predetermined temperatures for circulating outdoor air over one of said elements and into the enclosure when said thermostatic means is satisfied and for circulating air from the enclosure over said one of said elements and back to the enclosure upon a demand for heat by said thermostatic means, said refrigerating machine remaining inactive when the outdoor temperature is within said range.

EUGENE R. AMBROSE. 

